Tuesday, January 4, 2011

ACL Rehabilitation – Clinically Cleared But Ready to Play?

Anterior cruciate ligament injuries are all too common in competitive athletes. ACL ruptures are usually followed by reconstruction surgery that is then followed by progressive rehabilitation that may last up to 12 months. Depending on the extent of injury, most players can expect 6-12 months before being cleared by a physician to return to their previous level of play. However, some athletes seem to take much longer to complete a full recovery and a few never return to the competitive level that they once experienced. An Australian study addresses this apparent disparity between the clinical evaluation and competitiveness. Researchers show that despite being clinically cleared to play, many ACL injured athletes do not return to full competition one year after surgery.

The study examined 503 male and female patients who participated in a variety of sports (Australian football, basketball, netball and soccer). All had suffered a rupture of the ACL and underwent arthroscopic reconstruction surgery using a hamstring tendon autograft. After surgery, each athlete followed a progressive rehabilitation program. At 12 months post-surgery, subjects underwent a clinical exam and completed a questionnaire about their level of sports participation (that is, their return to play).

Most of the athletes were clinically cleared for full participation by 9 months and all were cleared by 12 months. Despite this, only 33% had attempted full competition, 34% had attempted training with modified play while 33% had not attempted to train or play.

Of the two-thirds who had not returned to full competition, almost half indicated that they indented to return to full play, 13% had given up competition because of knee issues, 12% had given up competition for other reasons and the remainder did not indicate whether they intended to return or not.

The results indicate that despite all players being clinically cleared for full participation after a 12-month rehabilitation, only 1/3 had actually done so. Another 1/3 hoped to return to their pre-injury level of play but the remaining third had ended their competitive playing careers.

Why do so many players fail to return to full competition despite being clinically cleared after surgery? One reason is psychological. The researchers point out an earlier study that shows many ACL injured athletes lack confidence and fear the risk of re-injury, perceptions that persist well after rehabilitation and after being clinically cleared to play. Also, those who express these emotions are less likely to return to full completion than those who don’t.

A second reason may be muscular. A 1988 study of ACL injured patients revealed that despite being clinically cleared to play (after 12 months), quadriceps muscle atrophy and weakness remained. Knee extensor strength was depressed by 10-12% in the injured limb compared to the non-injured limb. The atrophy of the quadriceps was not readily apparent to the physicians performing the clinical exams. The lost of muscle mass was replaced by a gain in fat mass. Thus, the visible size of the thigh was not changed but its composition was. The lost muscle strength experienced by these athletes probably limits their performance on the field or court and prohibits them from fully competing.

These psychological and muscular issues facing an injured athlete may also be interwoven. Athletes who feel somewhat apprehensive or fear re-injury may limit their effort during rehabilitation. The result is that muscle atrophy and weakness persists. On the other hand, weakened quadriceps muscles after surgery may instill a lack of confidence and heighten re-injury worries.

It is important to point out that neither study fully described the rehabilitation program details. The subjects did not appear to be professional athletes. Thus the athletes probably underwent a traditional program involving both clinical rehabilitation and unsupervised exercises performed outside of the clinic. There is no way to gauge the intensity or level of participation in the programs. Professional athletes, in the other hand, have a number of clinicians and rehabilitation specialists working with them on a daily basis. One would expect that given this level of support, professional athletes would undergo a more focused and intense rehabilitation program. As a result, they would be more likely to return to play that the non-professional and return to play much sooner.

The overall message from these investigations is that some ACL injured players might be clinically cleared to return to full competition within a year after surgery. However, many may not be ready to compete at the previous competitive level. Despite going through a rehabilitation program, some may have deficits that limit their participation level. These deficits may be psychological and a fear of re-injury. They may be muscular - muscle atrophy and decreased quadriceps strength. In either case, coaches should understand that clinical exams determine the functional outcomes of ACL reconstruction surgery. They are designed to determine if the knee is healed, functional and stable. Such clinical exams cannot decide the readiness of an athlete to compete at their pre-injured level. It is up to the coach to help the player correct these psychological and muscular defects – to regain the confidence and rebuild the lost muscle mass needed to compete at a high level.


Ardern CL, Webster KE, Taylor NF, Feller JA (2010) Return to the preinjury level of competitive sport after anterior cruciate ligament reconstruction surgery. American Journal of Sports Medicine, DOI: 10.1177/0363546510384798.

LoPresti C, Kirkendall DT, Street GM, Dudley AW (1988) Quadriceps insufficiency following repair of the anterior cruciate ligament. Journal of Orthopaedic and Sports Physical Therapy, 9: 245-249.

Webster KE, Feller JA, Lambros C (2008) Development and preliminary validation of a scale to measure the psychological impact of returning to sport following anterior cruciate ligament reconstruction surgery. Physical Therapy in Sport, 9: 9-15.

Note: Thanks for Dr. Don Kirkendall for passing along these studies and pointing out the issue of “ready to play” in the post-injured athlete.